The invention relates in general to atmosphere treatment devices and in particular to a new and useful high-frequency ozonizer for ozonizing air or oxygen and for sterilizing water.
Ozonizers, especially the "Sienenssche ozonizer", have been known for a very long time. In this device, use is made of the discharge between two electrodes covered with a dielectric medium, the discharge being generated by an applied high-voltage alternating current. The electrodes in this may be plate-like or tubular.
In the course of years, a number of suggestions have been proposed both to make the energy consumption of the Sienenssche ozonizer more favorable and also to make the ozone production more efficient. Ozonizers which are driven by a high-voltage pulse generator and which comprises a gas discharge tube with two tubular, coaxially arranged electrodes, of which one is grounded and the other is connected with the high voltage, have proven to be advantageous (cf. e.g. U.S. Pat. No. 4,234,800).
It is now known that the ozone production increases with the applied frequency, however, it is also known that the heat loss likewise increases with the frequency. In the production of ozone by means of a corona discharge a considerable heating of the air or oxygen is takes place in the discharging space. However, with an increasing heating of the discharging space the ozone production decreases with an increasing supply of energy. It follows from this that the cost effectiveness in ozone production can be favorably influenced chiefly by reducing the heat problem. The common ozone generators driven with 50 Hz require a very high operating voltage (15-30 KV) and large vessels with a correspondingly expensive cooling system for a satisfactory ozone yield. However, this is no longer economically and technically justifiable in the case of smaller and average systems which are, for example, to be used with swimming pools or drinking water generators.
For this, high-frequency ozonizers have been developed which are usually driven by pulses. The discharge vessels can therefore be small, while the operating voltage is at 3-4 KV. However, the heating or cooling problem in all ozonizers remains to achieve a favorable energy balance (cf. e.g. EP-unexamined application No. 0088, 973; German Pat. No. 22 40 986; German Pat. No. 44 978). The energy problem and thus the avoidance of elevated heat with a sufficiently good ozone yield is however further aggravated when there is not much energy available, e.g. if the energy is obtained from solar batteries.
Accordingly, for the solution of the heat problem it has also been proposed to construct the inner electrode not tubularly, but as a solid metal cylinder and to join this cylinder in a form-fitting manner with the metallic end piece, which for its part is grounded. That is to say, the good heat-conducting grounding electrode pulls the forming heat outwards on the surface of the housing and thus aids the cooling effect of the air or oxygen flowing through. The aluminum layer deposited on the dielectric discharge tube and serving as the high-voltage electrode causes a diffusion of the surface area heat over the entire length of the discharge tube, when this layer is as long as the discharge tube. Moreover, the mirroring working inwards radiates the heat on the air flowing through. In this way, a very good evacuation of heat is therefore obtained without special cooling systems having to be used, and thus a good energy balance is achieved.
Another suggestion now is to use the water to be purified or sterilized itself instead of the inner electrode German Pat. No. 35 07 885.5). This means then that two concentric dielectric tubes (glass tubes) are necessary, between which the air to be ozonized can flow in and out without combining with the water. The discharge takes place between the metal layer applied to the outer glass tube and the water as a grounding electrode, since the distance between the two electrodes can be held sufficiently small. In this arrangement use is made of the fact that, with the corona discharge, UV-radiation in the range of 100-400 nm is generated. UV-radiation between 100 and 200 nm has an ozone-forming effect, so that the air in the double tube is still further ozonized. In addition, the water is sterilized by UV-radiation in the range 200-400 nm. The ozone produced is added to the thus already sterilized water for further refining. What is problematic with this arrangement is the external insulation of the high-voltage electrode. A further difficulty with all known ozonizers is that extremely dry air must be used, which necessitates an air-drying system that equals the true ozonizer in size and cost.